Fourteen people have been killed - among them at least 10 government soldiers - in fighting near the town of Shakhtarsk, according to a Ukraine military spokesperson.

Ukraine television station Channel 112 put the number of dead at 20 and said a Grad missile was used by pro-Russian separatists in the attack, some 15 miles from the site of Malaysia Airlines flight MH17, where crash investigators have just managed to reach.

Image Caption:Residents flee from shelling in the town of Shakhtarsk

Pictures published by Russian news agency Rianovosti showed what it claimed were wounded Ukraine combatants taken captive by rebels.

Other images showed bodies of Ukraine soldiers lying in the road beside a burnt-out armoured personnel carrier, and a picture of a soldier reportedly digging a grave for his dead comrades.

"In total it is known that 14 people died but the bodies of four of them have not been identified and could be Ukrainian soldiers or terrorists," said military spokesman Oleksiy Dmytrashkivsky.

Image Caption:A wounded Ukrainian soldier walks away from a helicopter with his comrades

He added that "so far we are talking about 10 Ukrainian servicemen dead" in the clash.

Ukraine forces have strengthened their military offensive against the rebels in eastern Ukraine since flight MH17 came down in July, killing 298 people.

The government claimed the aircraft was brought down by rebels using a surface-to-air missile supplied by Russia, a claim denied by Moscow.

The Shakhtarsk attack shattered a brief respite across the war-torn region as international experts arrived at the MH17 site to begin a delayed investigation into the crash.

Image Caption:Investigators have reached the MH17 crash site

More than 60 experts, including Dutch and Australians, are on the scene. "Recovery work starts immediately," the Organisation for Security and Cooperation in Europe said on Twitter.

The Ukraine military said it was relaunching a broader offensive against the rebels following a day-long ceasefire but they insisted troops would not carry out operations in the immediate vicinity of the site.

The military claims it had taken the village of Novyi Svit from rebels and begun operations to secure the volatile border with Russia.

Pro-Russian separatists are reportedly positioned in their two main strongholds of Donetsk and Luhansk.

Ukrainian forces have focussed efforts on trying to drive a wedge between the two cities.